The giant ice flows drifting down from the Sea of Okhotsk have provided an ideal platform for a handful of adventure-seeking divers who have opened and expanded dive businesses across the Hokkaido island.
With water temperatures hovering between 0 and -2 degrees, and anywhere between 30 centimeters and two meters of ice skimming the surface, safety procedures are strict.
Several triangular exit and entry holes are drilled with a chainsaw or massive ice-cutting machines, at least 150 meters out. The group sets up a base for protective operations, including a tent for warmth and changing. A rope, long enough to extend well beyond the dive site, is tethered to the ice and stays in the water at all times in case an emergency sweep of the area is necessary.
A one-to-two instructor-to-customer ratio is standard. Due to low visibility and extreme cold, dives do not usually exceed 10 meters in depth or 15 minutes in length.
No experience is necessary, however, and anyone 18 years of age or older can try. Depending on conditions, the season usually runs every weekend from the end of January through mid-March.